A vehicular steering locking device to protect a vehicle from theft is known (refer to a patent literature 1). In this vehicular steering locking device, when a biasing force of a coil spring is applied to a lock bar so that its tip can be fitted into a lock hole formed in a middle of an outer wall of a steering shaft coupled to a steering wheel, the steering shaft is put in a locked state. On the other hand, when an electromagnetic solenoid is energized by a battery to put the steering shaft in an unlocked state, the lock bar is pulled against the coil spring, and its tip is released from the lock hole.
Locking a steering against user's will while a vehicle is moving should be avoided because it has a severe influence on a “turn” which is one of basic functions of a vehicle. For this reason, a mechanism, such as an assist function to be activated when a vehicular steering locking device is operated, to prevent a transition to a user's unintended state is proposed.